Atmospheric DBD in air for biomedical application: From excitation emission to simulation of irradiation
Priyadarshini Rajasekaran, Philipp Mertmann, Nikita Bibinov, D. Wandke, W. Vioel, Peter Awakowicz
International Workshop on Diagnostics in Microplasmas March 2010 (Bochum)
An atmospheric pressure DBD comprising a single copper electrode covered with ceramic is energized by a high voltage pulse power supply; objects of high capacitance like the human body can serve as the opposite electrode. DBD in air is characterized using grounded electrodes of different profiles and electrode materials, through determination of plasma parameters like averaged electron density and electron energy distribution function. Optical emission spectroscopy (OES), current-voltage measurements, microphotography and numerical simulation are used. DBD operates in a filamentary mode with opposite electrodes of high conductivity (like aluminium and saline liquid); the plasma channels are stochastically distributed, are about 30 microns in diameter and last for approximately 20 ns. The emission intensity of N2(C-B) at 337.1 nm and N2 +(B-X) at 391.4 nm are expressed in terms of photons/sec by considering the efficiency and acceptance angle of the spectrometer. Electron distribution function and electron density in the plasma channel are calculated taking into account the gas temperature in the plasma channel, quenching of excited species by nitrogen and oxygen molecules, the number of channels in each voltage pulse, the duration of the channel and the frequency of the applied voltage. The efficacy of medically useful molecules like nitric oxide and ozone produced in air plasma can be assessed by simulation. The irradiation of the treated surface by these reactive molecules and by UV photons is simulated using the well-known air plasma chemical reactions and the measured emission spectrum.